armbrust etal



Feb 21, 1956 R. J. ARMBRUST ErAL 2,735,410

WATER BY-PASS REGULATOR FOR STEAM GENERATOR CONTROL MECHANISM Filed Machl, 1952 5 Sheets-Sheet l @mx @@aj n L k. 3 1| OOWMO /I Lw 2 H||i OO OoooL i Si Em m .nhl onmwooooooooHooowoooooo umm. Owwwwoooo OOHHUOOOwUwwW OOn mAH @NH .l n\\ um o m1 om m mw Feb- 21, 1956` R. J. ARMBRUST x-:TAL2,735,410

WATER BY-PASS REGULATOR FOR STEAM GENERATOR CONTROL MECHANISM 3Sheets-Sheet 2 Filed March l, 1952 D m m m Feb- 21, 1956 R. J. ARMBRUsTET AL 2,735,410

WATER BY-PASS REGULATOR FOR STEAM GENERATOR CONTROL MECHANISM C20-'fwwwINV NTO S.

United States Patent O Roy' J. Armbrust and Joseph E. La Rocque,assignors to Vapor Heating Corporation, a corporation of DelawareApplication March 1, 1952, Serial No. 274,362

Chicago, lll., Chicago, iii.,

S Claims.

The present invention relates to steam generator control systems andmore particularly to a water by-pass regulator for such systems.

The improved by-pass regulator of the present invention has,for-illustrative purposes, been shown and described in connection with asteam generator control system in which the delivery of uid fuel to thefire chamber is proportionately controlled in relation to the volume offeed water delivered to the boiler steam generator. Such steam generatorcontrol system includes a constant delivery pump and a by-pass regulatorso disposed in the system that the volume of feed water delivered to thesteam generator or boiler is a function of the extent to which water isby-passed from the delivery side of the pump back to the feed watersupply. The by-pass regulator involves in its general organization aby-pass valve having a spring loaded mechanism associated therewithwhich is actuated by steam pressure developed by the boiler so that theextent of opening of the valve is substantially directly proportional tothe generated steam pressure. As steam pressure rises above the pressurerequired to open the valve, the extent of opening thereof isprogressively increased to by-pass increasing amounts of feed water andthus reduce the effective delivery of water by the pump. At such time asthe by-pass valve becomes fully open, substantially all of the feedwater delivered by the pump is returned to the supply and practically nowater is delivered to the boiler.

The system further includes a flow-responsive control mechanism which isresponsive to the momentary rate at which feed water is being suppliedto the boil and the function of which is to automatically regulate thesupply of fuel to the burner, as well as to regulate the forced draft tothe latter to maintain a correct balance between fuel and air and thusre the boiler in a manner commensurate with the rate atv which water isbeing supplied thereto.

In a system of the character briey outline above, the delivery of feedwater and fuel are increased and decreased in relation to the demand forsteam and when there is no demand for steam at low iire, the delivery offuel and water may be temporarily discontinued. However, it has beenfound that in such systems, employing a water coil type of boiler, thatwhen the ow responsive control mechanism shutsoi-the supply if fueltemporarily and also shuts olf the circulation of-water, the residualheat in the tire chamber of the boiler evaporates the static waterremaining in the coils of the boiler and thus4 greatly increases thedeposition of scale therein and shorten their period of usefulness. Ithas also been found that upon retiring of the steam generator and theapplication of feed water to the hot dried out coils thereof, under thecontrol of the ilow responsive mechanism, there is an immediate tendencytoward the creation of superheated steam. This phenomenon reduces thelife of the boiler by contributing to the formation of 4cracks, in thetubing.

Efforts have been made heretofore to overcome the above limitations bycontinuously circulating water through the coils during the temporaryolf-tire condition, but it was found highly undesirable, since the coilsunduly cooled and thereby induced excessive deposits of soot duringretiring. The continuous circulation of water, built up pressures whichproduced hydraulic locking effects and thereby caused the ow responsivemechanism to return the generator to its olf-lire condition beforereestablishing an adequate steam supply.

The present invention is designed to overcome the above notedlimitations that are attendant upon prior control systems of the typebriefly outlined above and, toward this end, contemplates the provisionof a water bypass regulator, which when associated with control systemsof this character, will retard or delay the creation of an off-tirecondition of the steam generator when the delivered steam pressure risesabove a predetermined maximum until such time as a further predeterminedrise in steam pressure indicates that an off-fire condition is in factdesirable and at which time such an olf-fire condition is allowed toobtain. A

A principal object of the present invention, therefore, is to provide apressure responsive Water by-pass regulator which will function in themanner brietly outlined above and which will allow a relatively smallamount of water circulation through the steam generator coils to takeplace immediately after the lire is shut olf from the generator so as toabsorb a portion of the residual heat and prevent drying out the coilsduring such time as the steam pressure remains in the vicinity of thepressure Iwhich it attains when the off-tire condition is firstinitiated, but which will cause a complete by-passing of water and aconsequent termination of feed water supply to the boiler if a stillfurther and predetermined steam pressure rise takes place during theperiod that the tire is shut oit.

Another object of the invention is to provide a regulator which, afteran off-tire condition of the generator has been attained and a demandfor steam is resumed, will establish a limited tlow of feed water to thegenerator coils immediately prior to retiring of the generator so as toinsure that the coils will be filled with water when actual retiring ofthe boiler occurs, after which the system will operate in the usualmanner with the rate of flow of feed water to the boiler serving tocontrol the supply of fuel to the fire chamber as Well as the supply ofcombustion air under pressure.

A, preferred embodiment of the invention is. illustrated in theaccompanying drawing, wherein:

Fig. l is a. schematic diagramY of asteam generating system with-whicl1the improved feed water by-passv regulator has been incorporated andshowing the major components of the system;

Fig. 2 isv a. front elevationall view of the improvedl bypass regulatorcomprising the present invention;

Fig. 3 is a sectional view taken substantially along the line 3-3 ofFig. 2;

Fig. 4 is a perspective view, somewhat schematic in its representation,of a How-responsive control unit utilizedin connection withy the systemof Fig. l. Certain parts of the control unity are-broken away, and otherparts have been omitted as to` avoid masking other parts thereof whichwill facilitate-an understanding thev principles of operation of theby-pass regulator ofV Figs. 2 and 3.

Fig. 4a is asectional viewtaken substantially alongthe line 4a-4a ofFig. 4.

Fig. 5' is a front elevationalview if the complete control unit of'Fig.4;

Fig. 6 is aside elevational view of aVVK portion of the controlunitshown in Fig. 5;4 and Fig. 7 is a rear view of the structure.showninFig.' 6.

3 Steam generating system The schematic diagram of Fig. l discloses anoperable steam generating system. V It includes a number of more or lessconventional instrumentalities embodied in the system and affected bythe operation of the improved feed water by-pass regulator hereinafterdescribed. The steam generator is designated as a whole by the referencecharacter 10.

The generator 10 is of a known water tube type and is capable offunctioning either as a hot water boiler or as a steam generator. It iscomprised of several concentric groups of coiled tubing7 operativelyconnected together in series and identied at 12, 13, 14 and 15. Thespace 16 embraced by the coils 12 constitutes a heating chamber abovewhich is disposed the iire chamber 17. A fuel burner 18 is surmounted bya spray head or nozzle 19 which, when liquid fuel is employed, functionsas an atomizer.

Feed water is supplied to the boiler 10 from a reservoir 20, the waterbeing withdrawn from the reservoir and forced through the various coils12 to 15 inclusive of the boiler by means of a pump 21. The ow of thefeed water from the reservoir extends through conduit 22, pump 21,conduit 23, a flow responsive control mechanism 24 (further illustratedin Figs. 4 to 7 inclusive) and conduit 25 to the intake end of the outergroup 15 of the boiler tubing. A check valve 26 disposed in the conduit25 prevents reverse ow of water in the event of failure of the pump 21.Steam and hot water emerge from the generator through a conduit 27 andpass to a steam separator 28 wherein the residue of hot water isseparated from the steam for return to the reservoir Z through a conduit29. Steam may be drawn from the separator 28 through a conduit 30 havinga shut olf valve 31 associated therewith.

The upper end of the steam separator 28 is connected by a conduit 32 tothe upper end of a pressure chamber 33 associated with the improved feedwater by-pass regulator device 34 of the present invention. Theregulator is in the form of a valve assembly in which the inlet port ofthe valve per se thereof is connected through a conduit 35 to the feedwater conduit 23. The outlet port of the valve is connected through areturn conduit 36 with the reservoir 20. When the pressure of a steamissuing from the separator 28 rises above a predetermined maximum, thevalve element 37 of the bypass regulator 34 opens to divert feed waterfrom the conduit 23 through the conduits 35 and 36 to return the same tothe reservoir 20. The pump 21 has a constant output and thus the returnof water delivered to the generator through the conduit 25 is a functionof the proportion of water diverted through the conduits 35 and 36, thatis to say, is a function of the extent to which the valve 37 is opened.The valve 37 itself and the actuating mechanism therefor will bedescribed in detail subsequently and for the present it is deemedsufcient to state that the valve is spring loaded so that its opening isproportional to the generated steam pressure. By such an arrangement thevolume of Water delivered to the control unit 24 is reduced to theextent of the volume diverted back to the reservoir 20. The control unit24 is so designed as to control the delivery of fuel to the atomizingnozzle 19 in proportion to the flow of feed Water through the unit 24.Consequently the fuel delivered is proportionally reduced in relation tothe volume of water diverted through valve 37 hack to the reservoir 20.It will be evident-that as steam pressure rises above the pressurerequired to actuate the by-pass regulator 34, the delivery of feed waterto the control device 24 is reduced and vice versa.

The control mechanism 24 is responsive to the rate at which feed wateris supplied to the boiler at any moment and it is capable of instantlyand accurately regulating the supply of fuel and air for combustionpurposes to the burner 17. Y

Fuel, usually oil or gas, is supplied to the spray head or nozzle 19through a conduit 38 having disposed therein a valve 39 associated withthe control unit 24 and which controls the rate of fuel supplied to theburner. The valve 39, in turn, is automatically controlled in accordancewith the rate at which feed water is supplied at any particular instantto the boiler 10. In order to progressively vary the amount of fueldelivered by the valve 39 to the burner, the valve is provided with aspring pressed valve element 40 (Fig. 5) having a V-slot il formedtherein and communicating with the outlet port 42 for delivering fuel tothe conduit 38 leading to the spray head or nozzle 19. When the valveelement 40 is depressed, the effective valve opening is decreased tothereby decrease the amount of fuel passing through the valve andconsequently through the conduit 38 leading to the burner. When pressureon the valve stern 43 is relieved, the valve 40 is moved upwardly by thevalve spring 44 to increase the effective opening of the V-slot 41.

When oil is used as a fuel, compressed air is delivered to the sprayhead for atomizing purposes through a conduit 45 (Fig. l). The volume ofair supplied to the burner 17, in the form of a forced draft from ablower 46, is controlled by a damper 47 which is automaticallycontrolled by the flow control device 24 under the influence of the rateof feed water supplyA and, as a consequence, in accordance with the fuelsupply rate.

Flow control unit The control mechanism 24 is illustrated in some detailin Figs. 4 to 7 inclusive and comprises several appropriately formedbody castings 48, 49, 5h, 51 and 52 which, conjointly, constitute aself-contained unit. The body castings 4S, 49 and 50 are bolted togetherto form a housing having an interior cavity which is divided into twochambers 53 and 54 by a flexible diaphragm 55, the peripheral margin ofwhich is clamped between the opposing annular faces 56 and 57 of thebody castings 48, 49 and 50. The casting 5i! has a feed water inlet port58, while the castings 48 and 49 have a feed water outflet port 59leading to the boiler through the conduit 25. The diaphragm 55 has acentral opening through which there extends a shouldered bushing 60having a central opening 61 providing an orifice through which feedwater may ilow from the chamber 53 to the chamber 54. A tapered pin 62extends axially through the orifice 61 and thus constricts the latter toan extent dependent upon the axial position of the pin 62 relative tothe diaphragm 55. The lower end of the pin 62 is secured to the casting50.

From the above description it will be evident that the effective area ofthe orifice 61 may be varied by adjusting the axial position of the pin62. This adjustment is performed at the factory and ordinarily is apermanent one. Manifestly, when feed water passes through the unit 24,the diaphragm 59 will yield in proportion to the resultant hydraulicpressure differential between the two chambers 53 and 54.

An arm or pitman 63 is connected at one end to the diaphragm 55 and isconnected as at 64 to the distal or free end of a level arm 65 keyed orotherwise secured to a shaft 66 journalled in bushing 67. A hub 68 issecured to the shaft 66 at the end remote from the lever arm 65 and hassecured thereto the inner end of a spiral spring 68a, the outer end ofwhich is anchored to a cup member 69 disposed within the body casting51. The cup 69 is adapted to be held against rotation within the casting51 in any desired position of adjustment to vary the tension of thespring 68a which serves as a restoring means for the diaphragm 59 andaffords a definite load against which the diaphragm 55 operates.

A second shaft 70 coaxial with the shaft 66 is connected to the latterand is piloted in a third and hollow tubular shaft 71,'. The shaft 71 isformed with an arm 72 tothe free end of which is secured a crank pin 73.

An intermediate area of the Shaft 70, is milled on two sides, as shownat 74, 75 in Figs. 4 and 4a, to form a rotary valve element 76 ofgenerally rectangular cross section. The valve element 76 closely litsthe bore of the shaft '71 and normally functions as a closure for twoports 77 and 7S formed in the shaft 71. The port 77 is in continuouscommunication with the port 79 formed in a bushing 9fL xed in an openingin a casting 52, the said port 79 communicating with a supply port 80formed in the casting 52 and leading from a conduit 81 (see also Figs.4, 4a and 5) for supply of oil under pressure to the valve 76. The port78 communicates with an outlet slot 71@ `formed in the shaft 71` Theoutlet end of said slot "71n opens into the crank chamber 82 at alocation adjacent the crank arm 72. Another set of ports 83 and 84 arearranged in quadrature to the ports 77 and 78. The conduit branch 35a(see Fig. 1) is connected by conduit 35 to a pump 86 so as to supply uidfuel under pressure to ports 79, 80 leading to the valve 76. Anotherconduit 87 serves to return pressure fluid from the crank chamber S2 toa supply reservoir or oil tank 37a.

The ports S3 and 84 are connected through conduits 8S and S9 (Figs. 4and 4a) to a hydraulic motor in the form of two cylinders 90 and 91having respective pistons 92 and 93 reciprocable therein. The pistons 92and 93 are connected by rods 9d and 9S respectively to the crank pin 73.When the diaphragm 55 is subjected to a pressure differential it yieldsproportionately and produces a corresponding rotation of the shafts 66and 79. Thus the valve clement 76, which is integrally formed with theshaft 79, is rotated to an extent proportional to the deection of thediaphragm S5.

When feed water flow is initiated to the control device 2d, the movementof diaphragm 55 is transmitted to valve 7o so as to bring the entranceport 77 into communication with port S3, whereupon duid pressure isdelivered through conduit SS into cylinder 90 and thereby move thepistons 92 and 93 toward the right in Fig. 4. Simultaneously the ports84 and 78 are brought into communication so that fluid expelled bypiston 93 will discharge through conduit S9 through said ports 84 and'78 into channel '71a and thence through the crank chamber S2 andconduit 87 to the reservoir 87a. The resultant movements of the pistons92 and 93 are communicated through the rods 94 and 95, crank pin 73 andarm 72 to the shaft 71, thus causing the latter to rotate in the samedirection as the shaft 70 by a follow-up action. When the shaft 71 hasrotated to such an extent that the ports 77 and 78 are closed by thevalve portion 76 of the shaft 70 as shown in Fig. 4a, ow of oil to thecylinder 90 is terminated thus stopping the movement of the pistons. Bytracing the flow of motive iiuid under the inuence of the position ofthe valve 76, it will be seen that the hollow shaft 71 promptly followsany movement of the shaft 70 by a fast follow-up action and the forceexpended in rotating the shaft 71 is not derived from the shaft 7o butrather from the oil pump 86. As a consequence, any variation in the loadimposed upon the shaft 71 is not reflected in the load upon thediaphragm S. Thus, when movement of the shaft 71 is employed forcontrolling the operation of the fuel supply valve 39 and damper 47,variations in the force required to move these elements will notinfluence the response of the diaphragm 55 or the extent of movement ofeither controlled element.

When ever feed water is flowing, the valve element 76 will be in anoft-normal position and will remain so until a change occurs in the rateof flow. An increase in the rate of flow will cause the diaphragm 55 tomove upwardly thus enlarging the feed water orifice 61 while a decreasein the rate of iiow will cause the diaphragm to move inthe oppositedirection to diminish the effective size of the orifice 51. Should theow o f feed water be attenti terminated. the diaphragm will return toits normal. Pesition while at the same time a cam 9,6 (Fig. 1) mountedon the shaft 71 rocks a lever 97 to actuate a microswitch 98 and therebyopens a normally closed electrical circuit through a solenoid valve 99to shutl olf all delivery of fuel to the spray head or nozzle 19.

in order to regulate the fuel valve 39 and air damper 47- to properlyproportion the amount of fuel and air delivered to the lire chamber 17in proportion to the rate of passage of feed watenthrough the diaphragmorifice o1, a pair of adjustable cam plates 1 00 and 101 (Figs. 5, 6 and7) are provided. The cam plate 100 operates the fuel supply valve 3 9while the cam plate 1101 operates the damper 47. The c am plates aresupported on oppositely extending radial arms 10Z and-103 and areadjustable by means of sorews 104 s o that the cam surfaces Sint-a (Fig.7) and lilla (Fig. 6) are of such angularity as to bring about thecorrect degree of actuation of the valve and damper for each incrementc'l angular displacement of shaft 71.

The fuel supply valve 39 is provided with an actuating arm 105 whichcarries a carri roller 106 which bears against the cam surface 1005:.The movements of the cam roller 106 are transmitted to the valve stem43.

The damper 47 (Figi) is actuated by link connections including a link(Figs. 1 and 6) connected to a link 107 which is pivotally secured tothe upper end or" a supporting arm 10S (Fig. 6). The said link 107carries a cam roller 109 bearing against the cam surface foin. Movementsof the cam plate 101 imparts movements, through the roller 109, to thelinks 107 and 110 and these movements are transmitted to the damp-er 47.

The two arms 102, and 103 (Fig. 5) are integrally formed on a hub 111which is keyed to the shaft 71.

The pistons 92 and 93 of the control unit 24 (Fig. 4), the fuel valve 39(Fig. 5) and air damper 47 (Fig. 1) are shown in their intermediatepositions. Movement of the piston 92 to the right as seen in Fig. 4represents a movement which will increase the supply of fuel and air tothe burner 17. Thus, a counter-clockwise movement of the cams 10i) and101 (Fig. 5) increases the delivery of fuel while a clockwise movement(shown by the arrows in Figs. l and 6) of these cams decreases suchdelivery. ,in order to maintain a relatively steady movement of thecontrol unit 24 in a direction to increase the delivery of fuel and toinsure a quick movement of the unit when it is desired to shut off theVtire, valve 112Uis interposed in the conduit 8 8 for delivering pressurefluid to the cylinder 9i). This valve is of asymmetrical constructionwhereby it restricts the flow of fluid through conduit 88 into thecylinder 9i) and consequently retards the power movement of the piston92 in a direction toward the right in Fig. 4 but permits unobstructedtlow of the fluid in the opposite direction and therefore permits quickmovement of the piston 92 to the left in Fig. 4 so as to reduce orshut-off the delivery of fuel and establish an off fire condition of thesteam generator.

Water luy-pass regulator it has been previously pointed out that it isnot desirable to allow an off fire condition of the steam generator toobtain each time the steam pressure developed at the outlet 30 of theboiler rises above a predetermined maximum until such time as it hasbeen ascertained that such an off re condition is justified.VAccordingly, in order to prevent immediate and rapid movement of the camcarrying members 102 and 103 in a clockwise direction as viewed in Fig.5 to thus shut off the supply of fuel through the conduit 38 leading tothe burner, the improved feed water by-pass regulator 34 of the presentinvention is employed. As will be explained presently, the by-passregulator 34 is designed to maintain the cam members 100 and 101 insuchpositionsV that a low re condition is maintained in the steamgenerator when the pressure of steam in the conduit 32 risesr to 20except for a very small amount.

a predetermined maximum and to continue such low re condition in effectuntil a still higher predetermined maximum pressure has been attained atwhich time the valve 37 associated with the regulator 34 becomes fullyopened so as to by-pass substantially all of the feed water issuing fromthe pump 21 back to the reservoir When a still higher predeterminedmaximum pressure of steam in the conduits 30, 32 has been attained, theby-pass valve is fully opened and even this small amount of fluid isreturned to the reservoir so that no feed water whatsoever is conductedto the steam generator coils.

The operative relation which the feed water by-pass regulator 34 bearsto the herein described control system is clearly illustrated in Fig. 1.This regulator is adapted to vary the amount of water by-passed from thepump outlet conduit 23 and returned to the reservoir 26 in response tothe steam pressure developed in the conduit section 30. The amount ofwater not thus bypassed continues on to the ow control unit 24 andcauses operation of this device in the manner previously described tobring about certain conditions at the steam generator or boiler 111 tosatisfy the requirements for which the regulator 34 is especiallydesigned and which will be explained subsequently.

The by-pass regulator is shown in detail in Figs. 2 and 3. The regulatorinvolves in its general organization a lower valve assembly A, anintermediate yoke assembly B and an upper pressure chamber or diaphragmchamber assembly C.

The valve assembly A includes a generally tubular valve casing 117having an inlet port 114 communicating with the by-pass conduit sectionand an outlet port 115 which communicates with the return conduitsection 36 through an attachment nipple 116. The casing 117 is providedwith a central bore 118 therein, the lower end of which is threaded toreceive therein a removable and adjustable valve seat element 119providing a seat for the valve element 37. The valve 37 is carried onthe lower end of a valve stem 120 which extends centrally through thebore 11S and which is slidably disposed in a valve bushing 121. Asuitable seal 122 prevents passage of water upwardly along the valvestern 120. The valve 37 is maintained normally seated on the valve seatby means of a coil spring 123 which bears at its lower end against abushing 121 and at its upper end against the under surface of a pilotcollar 124 suitably mounted on the valve stem 120.

The yoke assembly B includes a yoke proper 125 which is carried at theupper end of an irregular shaped body 126 having attachment lugs 127formed thereon whereby the entire by-pass assembly may be mounted on astationary support. The lower end of the body 126 is provided with asocket portion 127 into which the upper end of the valve casing extendsand in which it is secured by means of a tangential lock bolt assembly128. A plurality of cap screws 129 serve to secure the yoke proper 125to the upper end of the body 126.

The yoke 125 is in the form of a casting having a vertical bore 130formed therein in which there is slidably disposed a tubular rack 131having rack teeth 132 formed on one side thereof. The nature andfunction of the rack together with its associated operating mechanismwhich is supported in the yoke 125 will be described presently.

The diaphragm or pressure chamber assembly C includes a lower body orbase member 133 and an upper cover member 134, the two members formingtherebetween the pressure chamber 33 across which there extends aflexible impervious diaphragm 135. The marginal portion of the diaphragmis clamped between the body portion 133 and the cover portion 134 bymeans of a series of bolts 136. The cover member 134 is provided with aninlet passage 137, communicating with the conduit section 32 (see alsoFig. 1) and with the interior of the pressure chamber 33 above thediaphragm 135. A diaphragm plunger 138 is slidably disposed in a bore139 provided in the body 133 and is provided with an enlarged head 141iunderlying the diaphragm 135 and in tace-to-ace contact therewith. Thelower end of the plunger 141) is guided in a bore 141 formed in theupper portion ot the yoke.

The lower end of the diaphragm plunger 149 carries a valve-operating rod142 which extends downwardly through the yoke proper and tubular rack131 and has its lower end designed for engagement with the upper end ofthe vatve stem 120 thus allowing the valve 37 to normally remain closedunder the inuence ot the coil spring 123.

From the above description it will be seen that downward movement of theplunger 138 will not occur until such time as sufficient pressure hasbeen built up in the pressure chamber 33 above the diaphragm to overcomethe resistance of the springs 143, 144.

Means are provided for adjustably varying the pressure exerted by thesprings 143, 144 on the plunger 138 so that the by-pass adapter unit maybe set to operate within a predetermined range. Accordingly, the upperend of the previously mentioned tubular rack 131 is adapted to bearagainst the under side of a spring seat 145 so that upward movement ofthe rack within the bore 130 will elevate the spring seat from itspositions of support on the yoke 125 and thus compress the springs 143,144 to increase the pressure thereof against an upper spring seat 146and the diaphragm plunger 138. Toward this end the yoke 125 is providedwith a transverse bore 147 therein, in which there is rotatablyjournalled a shaft 148 carrying a pinion 149 which meshes with the teeth132 provided on the rack 131. An operating lever 158 has itsmedialregions secured to a hub 151 adjustably secured, by a locking screwassembly 152, to the shaft 148 so that turning movement of the lever 15)about the axis of rotation of the shaft 148 will cause rotation of thepinion 149 and consequently impart vertical movement to rack 131. Asshown in Fig. 2 angular swinging movement of the lever in a clockwisedirection will cause elevation of the rack 131 while counterclockwisemotion thereof will cause lowering of the rack.

The upper portion of yoke 125 has secured thereto by means of studs 153a plate 154 provided with indicia marks indicating steam pressure inpounds, and with a series of apertures 155 adapted to receive a lockingpin 156, carried on the lever 150, to lock the lever in a selectedposition. In Fig. 4 the lever 150 is shown as being set at pounds ofsteam pressure and at this particular setting it is intended that whenthe pressure of steam in the conduit 30 and in pressure chamber 33exceeds a predetermined pressure the plunger 138 will move downwardlyagainst the opposing spring tension and move the valve element 37 fromits seat thus commencing the by-passing of feed water as previouslydescribed.

Still referring to Figs. 2 and 3 the body member 133 of the pressurechamber assembly C is provided with a laterally extending beam 157having an enlarged head portion 158 formed at the outer end thereof.Mounted beneath the beam 157 is an operating lever D comprising a pairof spaced parallel side members 159, 160 which are maintained in spacedrelationship by means of spacing stud 161. The arms 159, 160 straddlethe medial regions of the diaphragm plunger 13S and a pivot pin 162extends through the plunger 138 and provides a pivotal connection forboth side members of the arm assembly D on the plunger 138. The rear endof the arm assembly D is pivoted on a pin 163 carried by the bodyportion 133. The unbalanced weight of the forward or free portion of thearm assembly and the plunger 138 or in other words the normal forceexerted by the springs 143, 144 upwardly on the plunger 138 is sucientto maintain the arm assembly D in an elevated position, but withcapacity for vertical movements; there being sucient looseness in thepin connection 162 to permit the arm assembly D to assume' differentpositions in response to vertical' movements of the plunger 138.

A pin 164 extends across the two arm members 159, 160 and carries aroller 165 thereon. The roller 165 is designed for cooperation with afriction block 166 in a manner thatV will be described presently toretard or restrict downwardly swinging movement of the arm assembly D.

The friction block 166 is adjustably secured by means of an anchoringscrew 167 to a tiltable pressure plate 168 pivoted as at 169 to theenlarged head 158 of the beam 157. The plate 168 engages a plunger 169which extends into a bore 174i provided in the head-158 and the innerend of the plunger 169a bears against a spring 170 disposed within thebore 171'. The compression of spring 170 may be adjusted by a adjustingscrewA 171 threadedly received Withinthe bore 170'.

The friction block 166 is provided with a protuberance or lip 1.72 whichis positioned in the pathY of movement of the` roller 165 and itfunctions to restrain downward movement of the arm D and consequentlythe plunger 138 and the further opening of by-passA valve 37 until thesteam pressure rises slightly above the pressure setting of theby-passcontrol'.

When steam pressure in the pressure chamber 33 is below the settingofthe operating lever 150 as indicated in pounds of pressure on theindicia plate 155, the roller 165 occupies a position above the lip 172.As steam pressure rises in the conduit section 39, and consequently inthe pressure chamber 33, the plunger 138 forces the swinging armassembly D downwardly and the roller moves downwardly and approaches thelip 172. When the steam pressure attains the value for which the by-passinstrument is set, the roller engages the lip 172 and is retarded in itsdownward movement until such time as a predetermined higher pressure ofsteam has been developed.

In the control system illustrated, for the desired results, theadjusting screw 171 is manipulated so that the pressure of the spring171i upon the plunger 169EL and the plate 16S will force the plateagainst the block 166 and the roller 165 and prevent the latter fromriding over the lip 172 until such time as approximately 35 pounds ofpressure over and above the pressure for which the instrument is set, asindicated by the position of the lever 150, has been built up in thepressure chamber 33. At such time, the pressure of the roller 165against the lip 172 is sufficiently great as to cause the roller to snapor ride over the lip and allow a consequent lowering of the plunger 138with its attendant valve-opening action. Thereafter the roller 165 maycontinue to move downwardly on the surface 173 in response to saidaccumulated excess pressure thereby permitting the valve 37 to move toits fully open position and permitting concurrent movement of the shaft71 and its cam 96 (Figs. l and 5) to bring about the closing of the fuelnozzle valve 99. During this condition of operation the feed water pump21, blower 46 and fuel pump 86, all being operated from the same motor174, may continue, the oil pressure from pump 86 being by-passed throughpressure relief valve 175 to the return conduit 87.

The contour of the lip 172 is designed according to engineeringexigencies so that as the roller 165 will move upwardly over the lip 172in the event of pressure differential drop of approximately l pounds.Toward this end, the under surface of lip 172 is formed with a gradualslope 176.

When the by-pass regulator 34 is properly installed and adjusted in thecontrol system illustrated in Fig. l, the various parts of the systemare coordinated so that under conditions of normal fire and normaldemand for steam the arm assembly D is elevated and the roller 165 rideson the upper regions of the friction block 166. Under such conditionsthe by-pass valve 37 remains closed and there will be full delivery offeed water to the generator 10.

As the demand for steam decreases as evidenced by a rise in steampressure in the conduit section 13, and pressureycli-amber segu-1eplunger 140 is' forceedownward-ty and the roller 11654 movesdow"w'ardly*. Whenappr'oiiitmately the pressure for which theinstrlnnent'- lis s'et has been attainedV in the pressure chamber, theroller moves into engagement withA the lip 172 and by this time thevalve 37 has opened to an extent suiiic'ient to by-pass water through'the valve and decrease'y the: flow of water tothe control unit 24; TheresponseV of the control unit- 24 at this particular time' will be such'that a condition of low or one-third tire is maintained at the boiler. j

When the roller moves over the lip- 1:72l and: assumes a position' at ornear th'elower surface of the lip, the response of the control u'nit'24'y is such asA to shut oi the supply of fuel` and' air tothe burner18z but stillmaintain a small amount' of water circulation through thegenerator coils because of the con'ljnued'loper'ation of pumpv 21. Thereduced delivery of feed' water, 0f course', is due to a materiallydecreased flow of water' toY the unit 24' occasioned by a Wider openingof theA valv'e 37".

When the roller moves into the extreme' lower regions the valve 37 isfully open and'allV of the feed water issuing from the pump 21 isby-p'a'ssed soA that no` water isV fed to the control unit or totheboiler through the conduit 25.

From the above descriptionlit will be appreciated that the maintenanceof a small supply: of Water tothe boiler coils duringv the' initial loffre condition of the latter, while the roller is immediately below thelip 172, serves to prevent drying out of the boiler coils due toresidual heat in the tire chamber 17. By the same token, circulation ofa limited amount of feed water through the coils serves to preventdeveloping"flash steam in the boiler coils and the consequent creationof superheated steam when the steam generator again resumes operationwith a consequent tendency for the creation of thermal cracks.

After an on tire condition of the generator 10, a decrease in steampressure in the chamber 33 will allow the roller 165 to move upwardly onthe surface of the friction block 166 as previously described until itagain encounters the lip inclined surface of the lip 172. At this pointthe lip will prevent further upward movement of the roller until apressure differential drop of approximately l5 pounds is established inthe chamber 33. rfhe roller will then move upwardly over the lip, thuspartially closing the valve 37 and decreasing the amount of Waterby-passed to the reservoir 2) so that sufficient feed water is passed tothe control unit 24 to establish the previously described low oronethird lire condition; of the generator.

it will be evident to those skilled in the art that the new' principleof operation underlying the described feed water by-pass regulator issusceptible to a considerable variety of embodiments. It is to beunderstood therefore that the invention contemplates all modificationsin principle and structure as comes under the scope of the appendedclaims.

We claim:

l. In combination with a steam generator having a re chamber, a fuelline for delivering liuid fuel to said fire chamber, a fuel valve in thelluid line, a feed water conduit leading to said generator, and a pumpof uniform capacity for delivering feed Water through said conduit tothe generator; of means for varying the delivery of Water to thegenerator in relation to the steam pressuretherein and for varying thedelivery of fuel to the tire chamber in relation to the flow of water tothe generator comprising a normally closed bleeder valve communicatingwith the feed water conduit at a location intermediate the pump and thegenerator, a pressure actuated structure responsive to the steampressure in the generator and operatively associated with said bleedervalve to open the same to an extent commensurate with the steam pressuredeveloped in the generator and thereby vary the delivery of feed waterto the generator, a control unit interposed in the feed water conduitand ine 11 cluding an element responsive to the ow of water to thegenerator and operatively associated with said fuel valve forproportionately varying its open position in relation to the rate offlow of feed water to the generator, and means associated with saidpressure actuated structure for delaying further movement thereof when apredetermined maximum steam pressure is attained, said delaying meansbeing rendered ineffective upon the develop- -ment of a predeterminedhigher steam pressure in the generator.

2. The combination structure defined in claim l characterized in thatsaid delaying means comprising a lever connected near one end to saidpressure actuated structure and the other end of the lever beingswingably in a predetermined path, and a yieldable abutment positionedin the path of movement of the last mentioned end of said lever andadapted to be engaged by said lever at the extremity of a predeterminedmovement thereof inY response to the movement of said pressure actuatedstructure, said abutment being adapted to yield to release said leverand said pressure actuated structure for further movement when saidpredetermined higher steam pressure is developed in the generator.

3. A combination structure as deiined in claim 2 characterized in thatmeans are provided for varying the yieldable extent of said abutment soas to vary the amount of steam pressure required above said maximum torelease said lever and said pressure actuated structure for furthermovement. -4. The combination structure as defined in claim Elcharacterized in that the under-surface of said abutment constitutes acam surface whereby the said lever will readily return to a positionabove said abutment.

5. The combination structure as defined in claim 4 characterized in thatan anti-friction roiler is mounted on the end of said lever adjacentsaid abutment for engagement with said abutment.

References Cited in the iile of this patent UNITED STATES PATENTS726,442 MacDonald Apr. 28, 1903 1,480,942 McKee Jan. 15, 1924 1,670,615Eggleston May 22, 1928 1,821,112 Muren Sept. l, 1931 1,971,177 FrenchAug. 21, 1934 2,062,925 Ofeldt Dec. 1, 1936 2,405,573 Frisch Aug. 13,1946 2,422,178 Blizard June 17, 1947 2,493,678 Marini Ian. 3, 19502,536,184 Johnson Jan. 2, 1951 2,572,195 Proctor Oct. 23, 1951 2,573,680Arnold Nov. 6, 1951 2,599,872 Slonneger June 10, 1952

